Angiogenesis is the biological process whereby new blood vessels are formed. Aberrant angiogenesis is associated with several disease conditions including, e.g., proliferative retinopathies, rheumatoid arthritis and psoriasis. In addition, it is well established that angiogenesis is critical for tumor growth and maintenance. Tie2 is a single transmembrane tyrosine kinase receptor that has been localized to the endothelial cells of forming blood vessels and has been shown to play a role in angiogenesis. Tie2 ligands include the angiopoietins (e.g., Ang1, Ang2, Ang3 and Ang4). Blocking the interaction between Tie2 and one or more of its ligands is expected to have beneficial therapeutic effects in settings where it is advantageous to limit or block angiogenesis.
Antibodies to Tie2 are mentioned, e.g., in U.S. Pat. Nos. 6,365,154 and 6,376,653. Nonetheless, there remains a need in the art for novel molecules capable of binding to Tie2, especially anti-Tie2 antibodies that can block the interaction of Tie2 with one or more Tie2 ligands such as Ang2. Such molecules would be useful for various therapeutic and diagnostic purposes.